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Lateral Microstructures: Fabrication, Low Dimensionality Effects and Application to III-V Devices

Objetivo

Lateral microstructures can now be fabricated using the most advanced lithographic techniques. Combining these with molecular beam epitaxy (MBE) or metal-organic chemical vapour deposition (MOCVD), 1D and 0D nanostructures, new devices, and actual devicesof the smallest sizes can be made in order to examine their properties. In detail, the aims of the LATMIC Action were to:
-provide high-quality epitaxial structures as the basis for future fabrication
-develop lateral nanostructures at the state-of-the-art minimum scale (typically 30 nm)
-study the basic physical properties of the low dimensional nanostructures, both experimentally and theoretically
-investigate the limits of GaAs-based devices, and fabricate entirely new devices.
The fabrication and study of 1-dimensional and 0-dimensional structures has been undertaken. The applicability of nanometre scale technologies to explore the scale limit of both existing and entirely new devices has also been investigated. The study of transport effects at very low temperatures in high magnetic fields and of optical effects at the subpicosecond level have contributed to new concepts and novel devices.

World records have been reached in the nanofabrication of devices: smallest optical wires with good optical properties ever realized, with a 20 nm width, or fabrication of a lateral superlattice with 20 nm dots and 50 nm spacing.

Breakthroughs in transport properties include low dimensional ballistic devices, such as Fabruy-Perot interferometer with electron waves large effects in the conductance statistics of mesoscopic systems, demonstration of granular transport in a single electron transistor like device, and resonant tunelling through quantum wires and dots.

The optical properties of quantum wires have been studied, with the demonstration of 1-dimensional polarization effects, qualitative agreement of the absorption spectra with theoretical calculations, and size dependent carrier relaxation of different materials observed for the first time.
APPROACH AND METHODS
The materials are grown by MBE, including GaAlAs/GaAs or InGaAlAs/InGaAs heterojunctions and quantum wells. Modulation-doped heterostructures with very high mobility are fabricated. MOCVD and CBE are used for realising InGaAs/InP layers.
Nanometre-scale structures are being fabricated using high-voltage and high-resolution electron-beam lithography. Focused ion-beam systems enable the localised implantation of dopants into layers and localised etching. Masked implantation techniques are also employed. The formation of Ohmic and Schottky contacts are investigated.
In order to perform an extensive range of physical investigations, temperatures as low as 0.01 K and magnetic fields up to 14 Tessla have been used. The properties studied are as follows:
-transport properties in 1D structures, including ballistic transport and quantum coherence effects
-resonant tunnelling through 1D and 0D structures
-optical properties of 1D and 0D structures or arrays, including excitation, luminescence and Raman scattering.
Theoretical studies and computer modelling have been undertaken to better understand resonant tunnelling, elastic and inelastic scattering mechanisms, and quantum interferences.
PROGRESS AND RESULTS
World records have been reached in the nanofabrication of devices: smallest optical wires with good optical properties ever realized, with a 20 nm width, or fabrication of a lateral superlattice with 20 nm dots and 50 nm spacing.
Breakthroughs in transport properties include low-dimensional ballistic devices, such as Fabruy-Perot interferometer with electron waves, large effects in the conductance statistics of mesoscopic systems, demonstration of graular transport in a single electron transistor-like device, and resonant tunelling through quantum wires and dots.
The optical properties of quantum wires have been studied, with the demonstration of one dimensional polarization effects, qualitative agreement of the absorption spectra with theoretical calculations, and size dependent carrier relaxation for different materials observed for the first time.
POTENTIAL
This Action leads to important breakthroughs in submicron technologies with high relevance to future devices. The European Community has gained advanced expertise in e-beam lithography down to 20 nm, localised implantation and determination of its resolution limits, and metal deposition and etching at scales smaller than 0.1 micron.

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Coordinador

Centre National de la Recherche Scientifique (CNRS)
Aportación de la UE
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Dirección
1919 route de Mende
34405 Montpellier
Francia

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Participantes (6)